Lawn-mower.



A. C. BOND.

LAWN MOWER. APPLICATION FILED MAR.13.1912.

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Patented NOV. 19, 1912.

ALFRED C. BOND, OF LENOX, MASSACHUSETTS.

LAWN-MDWER.

intensa.

Application led March 13,

To all whom it may conccm: y

Be it known that I, ALFRED C. BOND, a subject of the King of GreatBritain, residing at Lenox, in the county of Berkshire and State ofMassachusetts, in the United States of America, have invented certainnew and useful Improvements in Lawn-Mowers, of which the following is aspecification.

My present invention relates to lawn mowers and has for its object toimprove the cutting mechanism thereof, and, more particularly, thestationary knife, or cutter plate, and its securing means.

rIhe stationary knife which I employ is formed of spring metal and hasfor its distinctive feature a series of spaced notches distributed alongits front edge, the intervening teeth being provided with straightcutting edges in substantial alinement parallel to the axis of therotary knife. n

I am aware that cutter blades have been previously formed of springmetal and that such blades have also been constructed with a serratedfront edge. In my prior application, Serial Number 595,349, filedDecember 3, 1910, in relation to lawn mowers, I have shown a devicewhich combines bot-h of these features, but in all previous knowndevices of this character whichare provided with a serrated stationaryblade, the sei-rations are formed or arranged so as to intercept oneanother and form a continuous series, they teeth being pointed and thenotches cleft relatively well down, as in the manner of the ordinarytype of -a carpenters saw. I find this construction objectionable in thepresent device by reason of the fact that the blades of the rotary knifein vpassing obliquely along the edge of the stationary blade arecontinuously in contact with at least two adjacent teeth of the latter,so that there is no release of or change in the tension exerted by oneblade upon the other. Moreover, in previous types of stationary bladeswhich are provided with a series of serrations, the oblique edges of thenotches which form the sides of the teeth constitute the cuttin edges,while in my present device the notc es are made relatively smaller andspaced apart so that the cutting edges of the several teeth are inalinement at an angle to the edge of the rotary blade, which fact Iregard as an advantage over previous known forms of serrated blades.Further, the notches are so spaced apart that the edge of the rotaryknife in wiping the stationary blade takes Speciication of LettersPatent.

Patented Nov. i9, i912.

1912. serial No. 683,598.

succeeding after passing through a given notch, the sudden strong impactof the engaging parts due to a slight variation in level of the bladesat the point of Contact, givesan increased biting force which isdirected upon the intervening blades of grass. Instead, therefore, ofthe usual uniform tension between the engaged cutting blades and thefixed cutting power of a given propelling force applied to the mower, Iprovide with the same propelling force a rapid alternation in theapplication and release of tension between the knives and thus obtain agreater cutting etliciency through a series of short strokes of higherinitial power. The action of a pair of ordinary hand shears in cutting apiece of cloth is suggested as illustrative of the operation of mydevice, although not wholly parallel. In the latter-instance theoperator commonly iinds that a series of short strokes of the opposingblades upon the work where the incisive force is rapidly released andrenewed and the relative positions of the blades at initial engagementforms a sharper angle, is more effectual than one continuous stroke, ifthe work oifers sensible resistance.

F or the purpose of increasing or reducing the tension between theengaging blades at a given point, I further provide auxiliary means inthe clamping devices forsecuring the stationary blade on the carrier, aswill be lhereinafter more fully set forth.

Having described the general character, purpose and operation of myinvention, I will proceed to describe a specific useful form ofembodiment thereof, whereinl Figure l is a top view of my stationarycutting blade; Fig. 2, a bottom view of the same; Fig. an end view ofthe same; Fig. 4 n. sectional bottom view of the stationaryblade asmounted on the carrier, showing the relation of the clamps thereon; Fig.5, a detail sectional view of the cutting edge of the stationary bladeand indicating the relative position of the rotary knife, the effects ofwear upon the several teeth by the engagement of these parts being alsoillustrated; Fig. 6, a transverse sectional view offtheassembled cuttingmechanism employed in an ordinary forni of lawn mower', preferred formof my invention is embodied; F ig. 7, a cross-section of the carrierwith the parts of my invention mounted thereon, and showing the relativeposition of the blade on the carrier when the tension exerted by thestationary blade upon the rotary blade has been increased by theadjustment of the set-screw in the clamp; and Fig. S, an edge or sideview in detail of the body of the clamp.

The rotary cutter or reel 1, mounted upon a shaft 2, is shown asprovided with a plurality of spirally arranged blades 3, 3, etc., thefront edges of which are preferably beveled and adapted to successivelybarely engage the stationary blade or plate 4. which is removablysecured on a horizontal support or carrier 5 and positioned in the pathof the blades 3, 3, adjacent the surface of the ground, wherebytheblades of grass are severed as the mower travels forward. The carrier5 is supposed to be supported at its ends in adjustable relation on theframe of the mower (not shown), the carrier being adjusted verticallyfor truing-the position of the plate 4 with relat-ion to the rotaryblades 3, 3, etc.

The stationary blade 4 is preferably made uniformly thin and constructedof spring metal with sufficient resiliency to yield somewhat to thepressure of the rotary knives, resuming its normal position upon therelease of such pressure. The blade 4 is provided with a series ofbeveled notches 6, 6,

. etc., formed on the underside lof the front edge and extendingslightly through on the upper side of the blade, the extreme edge of theblade being also slightly beveled on its underside, as shown at 7, Fig.3. Said notches 6, G, are distributed along the blade at substantiallyuniform distances apart, providing in eect a series of fiat-headed teethS, S, etc., which present. a straight cutting edge parallel to the axisof the rotary knife. The sizes and proportions of the several teeth andnotches respectively are such that the line of the rotary bladetraveling at an angle over the blade 4, as shown in Fig. 5, fallsslight-ly as its enters the notch and again rises when clearing. Therotary blade, after entering one of the notches 6, is brought intoabrupt engagement with the adjacent end of the proximate tooth, which inforcing the rotary blade slightly upward again to its normal position onthe front edge of the tooth, causes an increase of tension between theengaging blades which etfectually severs the interven ing blades ofgrass. .The resulting impact of the blades succeeding each notch in thestationary blade produces a biting effect wherein a l with superiorcutting powers upon the grass,

which forms the object of my invention.

The stationary blade 4 is shown as secured on the carrier 5 by means ofa plurality of individual clamps 10, 10, distributed along the carrierand secured thereto by means of screws 11, 11 etc., projecting through atransverse opening through the body of the clamp. The front end of theclamp 10 is constructed with a lip 12, inclined slightly upward on itsinner face, which projects upon the lower side of the stat-ionary bladeforward to a. point somewhat beyond the edge of the carrier, as shown inFig. 4. The body of the clamp forms a shoulder at 13, over the rear endof the lip 12, which prevents rearward displacement of the blade. Toregulate the tension or pressure of the clamp upon the blade 4 at agiven point l provide a. setscrew 14 seated in a tapped opening 15provided in the rear of the screw 11 and extending through the body ofthe clamp, said screw 14 being disposed preferably over aV slight ledgeor shoulder 16 normally provided on the carrier and adapted to engagetherewith. To increase the tension between the engaging blades 3 and 4at a given point, the screv7 10 in the clamp nearest the point desiredis slightly loosenedwhile the setscrew 14 is then screwed down below theclamp thereby slightly raising the rear end and affording sutticientthrust to cause the front end of the clamp to bear upward upon the blade4 with increased pressure.

I claim 1. 1n lawn mowers having a rotary blade, a stationary blade ofresilient metal having a cutting edge provided with a series of teethlhaving three sides each, one of such sides being substantially parallelto the axis of the rotary blade and forming the main cutting portion ofthe edge of the stationary blade.

2. In lawn mowers having a rotary blade, a stationary blade of thinresilient niet-al having its front side provided with a series of slightnotches spaced apart relatively to each other, each of the teeth formedb v the intervening notches being constructed to form a three-sidedelement, one of the sides of each tooth being in alinenient with thecorresponding sides of the remaining teeth and constituting therewith acutting edge substantially parallel` `to\the axis of the rotary blade.

In testimony whereof I hereunto atiix my signature in presence of twoWitnesses.

ALFRED C. BOND. VVit-nesses JNO. J. VHITTLESEY, MICHAEL L. EISNER.

